CS 111 w20 lecture 18 outline

1 Practice

1.1 Mystery

class   A:
    def __init__(self, x):
        self.x = x

    def bump(self, i):
        self.x += i

class   B:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def bounce(self, i):
        if i % 2 == 0:
            self.y += i
        self.x += i * 2

x = 7
a = A(x)
a.bump(2)
b = B(a.x, x)
b.bounce(1)
b.bounce(2)
print(x, a.x, b.x, b.y)

1.2 Rectangle Class

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y
  • define a Rectangle class with three instance variables: a Point for the upper left corner, a width, and a height
  • add a get_corners method to the class that returns a list of the rectangle's four corners

1.3 Fraction Class

What's missing from the definition? 

class Fraction:
    def value():
        return top / bottom

class Fraction:
    def __init__(self, top, bottom):
        self.top = top
        self.bottom = bottom

    def value(self):
        return self.top / self.bottom
  • Are we able to treat these as fractions?
    • Fraction(3, 4) == Fraction(3, 4)
      • add an __eq__ method
    • Fraction(1, 2) < Fraction(3, 4)
      • add a __gt__ method
    • Fraction(1, 2) + Fraction(3, 4)
      • add a __add__ method

2 Cuckoo Class

class Cuckoo:
    def __init__(self, steps):
        self.steps = steps
        self.count = 0

    def tick(self):
        self.count += 1
        if self.count == self.steps:
            print("CUKCOO!!")
            self.count = 0
        else:
            print("tick...")

    # more concise version using %
    def tick(self):
        self.count += 1
        if self.count % self.steps == 0:
            print("CUKCOO!!")
        else:
            print("tick...")

3 Lab 6 Warmup

4 Quiz